i recived a GPS for Christmas... one of those Garmin ones that you can use with your bike and i set up a Strava account... they are one of the sponsors of are team... Strava lets you download your ride, calculates your power output, shows a map of where you road, lets you compare and compete with others on climbs, gives an easy to read line graph of heart rate, elevation , power, distace and speed.... all in one cart... its also a social networking type of site you can follow other riders and comment on their rides... i am liking it so far... it has made me more motivated to ride.
the Strava site...
http://app.strava.com/about